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Researchers link ‘bottle to sleep’ and dental risk in new study
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Freya Lucas
Mar 25, 2025
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New research, led by the University of Sydney, has linked giving babies and toddlers bottles to help them sleep with dental cavities and the risk of being overweight in early childhood.
Published last week in the Australian and New Zealand Journal of Public Health, the research used data collected on over 700 toddlers involved in Western Sydney University’s Healthy Smiles Healthy Kids (HSHK) study – a cohort study that followed children from birth.Researchers analysed the results of a survey of mothers, as well as dental checks and body measurements and considered other factors that could influence dental hygiene and weight, finding that:
- More than 30 percent of children were still bottle fed to sleep at two years old;
- Children who were bottle fed to sleep at two years old were almost twice as likely to have overweight in early childhood;
- Children who were bottle fed to sleep at three years old had nearly twice as many teeth affected by tooth decay in early childhood.
Lead author Heilok Cheng said that parents and carers “want to do the right thing” but may not be aware of the health risks of bottle feeding before naps and at bedtime.
“Australian recommendations advise parents to start introducing cups at 6 months of age and stop using baby bottles at 12 months,” she said.
“Bottle feeding in bed is not recommended at any age. Our research now provides a much more robust evidence base for that advice.”
Common drinks for toddlers, including cows milk and formula, often contain either natural or added sugars, increasing the risk of tooth decay.
“When a bottle is offered at bedtime it’s often being used by carers to calm an unsettled child or encourage the child to drift off to sleep,” Ms Cheng said. “Because the bottle isn’t being offered in response to hunger, it can lead to overfeeding, putting children at risk of unhealthy weight gain.”
Instead, she continued, parents need support to help them to avoid building bad habits, so that future generations are “set up for a healthy future” from the start.
A common myth is that dental health is less important for young children because they still have ‘baby teeth’, however researchers noted that dental decay in childhood is more likely to result in poor dental outcomes later in life.
For further support, Ms Cheng recommended that parents seek guidance from trusted healthcare professionals and reputable resources such as Primary Health Providers and dentists to ensure their child's health and development is on track.
The HSHK study is led by Western Sydney University in collaboration with the University of Sydney, Sydney Local Health District, South Western Sydney Local Health District, University of Queensland, University of Technology Sydney, and Curtin University. It is funded by the Australian National Health and Medical Research Council, NSW Health, Australian Dental Research Foundation, and Oral Health Foundation.
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